For sizing, I'd get ML if your LO is borderline on the rise of their current diapers, but not the width. I'd get L if they are really on the edge of both or if you want a lot of extra growing room.

I only saw sizing by weight on the website, so I couldn't tell on the width... measurements would he helpful... I feel like everything I have in a L is big on him everything I have in a M is small on him, and sizing is always varied with pattern anyway and some of my "L" diapers are 6-8 years old and have no tags ... so I have no idea where they came from, and the one with a tag apparantly went out of business loooong ago, which is too be because that Fuzzy Fannies pocket I have is pretty adorable and the ONLY pocket I've hung onto all these years. It's vintage

Anyway, I digress.... I definitely would want this diaper to last, so I tend to size up...

The ML and L have the same rise, only the width is different...there are pics on the buy swap trade group on facebook and comparison pics of the different sizes...and on Monday they are doing a 3 for $90 deal ( wish I had known before I ordered 5!).